Ceramic metal composite substrate

Abstract

A ceramic metal composite substrate includes a metal core layer, two soldering layers, and two ceramic covering layers. The metal core layer is a metal-diamond composite layer, and the metal core layer has two metallic surfaces spaced apart from each other along a thickness direction by a predetermined thickness. The two soldering layers are respectively formed on the two metallic surfaces. The two ceramic covering layers are respectively fixed to the two metallic surfaces through the two soldering layers. Each of the two ceramic covering layers has a heat-transfer coefficient greater than or equal to 20 W/m·k, and a sum of thicknesses of the two ceramic covering layers and thicknesses of the two soldering layers is less than or equal to the predetermined thickness. Each of the two ceramic covering layers overlaps at least 80% of an area of the corresponding metallic surface along the thickness direction.

What is claimed is: 
     
         1 . A ceramic metal composite substrate, comprising:
 a metal core layer having two metallic surfaces spaced apart from each other along a thickness direction by a predetermined thickness, wherein the metal core layer is a metal-diamond composite layer;   two soldering layers respectively formed on the two metallic surfaces of the metal core layer; and   two ceramic covering layers fixed to the metal core layer through the two soldering layers, respectively, wherein each of the two ceramic covering layers has a heat-transfer coefficient being greater than or equal to 20 W/m·k, and a sum of thicknesses of the two ceramic covering layers and thicknesses of the two soldering layers is less than or equal to the predetermined thickness;   wherein each of the two ceramic covering layers overlaps at least 80% of an area of the corresponding metallic surface along the thickness direction.   
     
     
         2 . The ceramic metal composite substrate according to  claim 1 , wherein the metal core layer is made of a material including at least one of copper, silver, and aluminum, and each of the two ceramic covering layers is an aluminum nitride (AlN) layer that is sintered to the metal core layer through the corresponding soldering layer and that has a thickness being within a range from 5 μm to 350 μm. 
     
     
         3 . The ceramic metal composite substrate according to  claim 1 , wherein the metal core layer includes a plurality of diamond particles provided as an aggregate and at least one of copper, silver, and aluminum that is mixed in the diamond particles. 
     
     
         4 . The ceramic metal composite substrate according to  claim 3 , wherein the metal-diamond composite layer is a copper-diamond composite layer, a copper-aluminum-diamond composite layer, an aluminum-diamond composite layer, a copper-silver-diamond composite layer, a silver-diamond composite layer, or an aluminum-silver-diamond composite layer. 
     
     
         5 . The ceramic metal composite substrate according to  claim 1 , wherein each of the two soldering layers is a brazing paste or a glass paste, and a thickness of any one of the two ceramic covering layers is greater than or equal to a thickness of the corresponding soldering layer that is less than or equal to 30 μm. 
     
     
         6 . The ceramic metal composite substrate according to  claim 1 , wherein each of the two ceramic covering layers has a grinding plane arranged away from the metal core layer. 
     
     
         7 . The ceramic metal composite substrate according to  claim 6 , further comprising two circuit layers respectively formed on the grinding planes of the two ceramic covering layers in a direct plated copper (DPC) manner or in a thin film metallized substrate forming manner. 
     
     
         8 . The ceramic metal composite substrate according to  claim 7 , wherein at least one of the two ceramic covering layers has a thru-hole that is recessed from the grinding plane thereof to the corresponding soldering layer, and a corresponding one of the two circuit layers is filled to occupy an entirety of the thru-hole so as to be connected to the corresponding soldering layer. 
     
     
         9 . A ceramic metal composite substrate, comprising:
 a metal core layer having two metallic surfaces spaced apart from each other along a thickness direction by a predetermined thickness, wherein the metal core layer is a metal-diamond composite layer; and   two ceramic covering layers respectively formed on the two metallic surfaces of the metal core layer, wherein each of the two ceramic covering layers and the corresponding metallic surface jointly form a eutectic-bonding layer therebetween, and wherein a sum of thicknesses of the two ceramic covering layers is less than or equal to the predetermined thickness, and each of the two ceramic covering layers includes:
 a first ceramic sublayer fixed onto the corresponding metallic surface through the corresponding eutectic-bonding layer; and 
 a second ceramic sublayer formed on the first ceramic sublayer, wherein the second ceramic sublayer has a heat-transfer coefficient being greater than or equal to 20 W/m·k; 
   wherein each of the two ceramic covering layers overlaps at least 80% of an area of the corresponding metallic surface along the thickness direction.   
     
     
         10 . The ceramic metal composite substrate according to  claim 9 , wherein the metal core layer is made of a material including at least one of copper, silver, and aluminum, and each of the two ceramic covering layers is eutectic-bonded to the metal core layer in a direct bonded copper (DBC) forming manner, and a thickness of any one of the two eutectic-bonding layers is less than or equal to 3 μm, and wherein, in each of the two ceramic covering layers, the first ceramic sublayer is an aluminum oxide (Al 2 O 3 ) layer having a thickness within a range from 5 μm to 15 μm, and the second ceramic sublayer is an aluminum nitride (AlN) layer having a thickness within a range from 5 μm to 350 μm. 
     
     
         11 . The ceramic metal composite substrate according to  claim 9 , wherein the metal core layer includes a plurality of diamond particles provided as an aggregate and at least one of copper, silver, and aluminum that is mixed in the diamond particles. 
     
     
         12 . The ceramic metal composite substrate according to  claim 11 , wherein the metal-diamond composite layer is a copper-diamond composite layer, a copper-aluminum-diamond composite layer, an aluminum-diamond composite layer, a copper-silver-diamond composite layer, a silver-diamond composite layer, or an aluminum-silver-diamond composite layer. 
     
     
         13 . The ceramic metal composite substrate according to  claim 9 , wherein the second ceramic sublayer of each of the two ceramic covering layers has a grinding plane arranged away from the metal core layer. 
     
     
         14 . The ceramic metal composite substrate according to  claim 13 , further comprising two circuit layers respectively formed on the grinding planes of the two ceramic covering layers in a direct plated copper (DPC) forming manner or in a thin film metallized substrate forming manner. 
     
     
         15 . The ceramic metal composite substrate according to  claim 14 , wherein at least one of the two ceramic covering layers has a thru-hole that is recessed from the grinding plane thereof to the corresponding eutectic-bonding layer, and a corresponding one of the two circuit layers is filled to occupy an entirety of the thru-hole so as to be connected to the corresponding eutectic-bonding layer. 
     
     
         16 . A ceramic metal composite substrate, comprising:
 a metal core layer having two metallic surfaces spaced apart from each other along a thickness direction by a predetermined thickness, wherein the metal core layer is a metal-diamond composite layer; and   two ceramic covering layers respectively formed on the two metallic surfaces of the metal core layer, wherein each of the two ceramic covering layers and the corresponding metallic surface jointly form a diffusion-bonding interface therebetween that has a thickness of less than or equal to 1 μm, and wherein each of the two ceramic covering layers has a heat-transfer coefficient being greater than or equal to 20 W/m·k, and a sum of thicknesses of the two ceramic covering layers is less than or equal to the predetermined thickness;   wherein each of the two ceramic covering layers overlaps at least 80% of an area of the corresponding metallic surface along the thickness direction.   
     
     
         17 . The ceramic metal composite substrate according to  claim 16 , wherein the metal core layer is made of a material including at least one of copper, silver, and aluminum, and each of the two ceramic covering layers is an aluminum nitride (AlN) layer having a thickness within a range from 5 μm to 350 μm. 
     
     
         18 . The ceramic metal composite substrate according to  claim 16 , wherein the metal core layer includes a plurality of diamond particles provided as an aggregate and at least one of copper, silver, and aluminum that is mixed in the diamond particles, and the metal-diamond composite layer is a copper-diamond composite layer, a copper-aluminum-diamond composite layer, an aluminum-diamond composite layer, a copper-silver-diamond composite layer, a silver-diamond composite layer, or an aluminum-silver-diamond composite layer. 
     
     
         19 . The ceramic metal composite substrate according to  claim 16 , wherein each of the two ceramic covering layers has a grinding plane arranged away from the metal core layer, and wherein the ceramic metal composite substrate includes two circuit layers respectively formed on the grinding planes of the two ceramic covering layers in a direct plated copper (DPC) forming manner or in a thin film metallized substrate forming manner. 
     
     
         20 . The ceramic metal composite substrate according to  claim 19 , wherein at least one of the two ceramic covering layers has a thru-hole that is recessed from the grinding plane thereof to the corresponding diffusion-bonding interface, and a corresponding one of the two circuit layers is filled to occupy an entirety of the thru-hole so as to be connected to the metal core layer.